Shaken baby syndrome is a term used to describe the constellation of signs  and symptoms resulting from violent shaking or shaking and impacting of the   head of an infant or small child. The degree of brain damage depends on the  amount and duration of the shaking and the forces involved in impact of the head. Signs and symptoms range on a spectrum of neurological alterations from minor (irritability, lethargy, tremors, vomiting) to major (seizures, coma, stupor, death). These neurological changes are due to destruction of brain cells secondary to trauma, lack of oxygen to the brain cells, and swelling of the brain. Extensive retinal hemorrhages in one or both eyes are found in the vast majority of these cases. The classic triad of subdural hematoma, brain swelling and retinal hemorrhages are accompanied in some, but not all, cases by bruising of the part of the body used as a "handle" for shaking. Fractures of the long bones and/or of the ribs may also be seen in some cases. In many cases, however, there is no external evidence of trauma either to the head or the body. (Definition provided by Robert Reece, M.D. Dr. Reece is a clinical professor of Pediatrics at the Tufts University School of Medicine.)

Approximately 20% of cases are fatal in the first few days after injury and the majority of the survivors are left with handicaps ranging from mild - learning disorders, behavioral changes - to moderate and severe, such as profound mental and developmental retardation, paralysis, blindness, inability to eat or exist in a permanent vegetative state.

In a response provided by Dr. John Lancon, he defined shaken baby syndrome as the constellation of non-accidental intracranial and ocular hemorrhages occurring in infants and young children. Other injuries, including cutaneous bruises, lacerations, burns, parenchymal brain injuries, rib fractures, extremity fractures, and injuries to various internal organs may be seen in the setting of shaken baby syndrome, but are not required for diagnosis. Some experts have suggested changing the name of the syndrome to shaken impact syndrome to emphasize the importance of cranial impact in the genesis of the severe brain injury seen in some victims of shaken baby syndrome.

Immediate Consequences:

©Breathing may stop or be compromised

©Extreme irritability


©Limp arms and legs or rigidity/posturing

©Decreased level of consciousness

©Vomiting; poor feeding

©Inability to suck or swallow

©Heart may stop



Long-Term Consequences:

©Learning disabilities

©Physical disabilities

©Visual disabilities or blindness

©Hearing impairment

©Speech disabilities

©Cerebral Palsy


©Behavior disorders

©Cognitive impairment



©Babies' heads are relatively large and heavy, making up about 25% of their total body weight. Their neck muscles are too weak to support such a disproportionately large head.

©Babies' brains are immature and more easily injured by shaking.

©Babies' blood vessels around the brain are more susceptible to tearing than older children or adults.


©Often, perpetrators shake an infant or child out of frustration or anger. This most often occurs when the baby won't stop crying. Other triggering events include toilet training difficulties and feeding problems.


There are no firm statistics regarding the actual incidence of SBS/SIS since there are no central reporting registries to collect these data. However, estimates have been made based on clinical experience and extrapolated figures from hospitals caring for children. Estimates range from annual figures as low as 600 cases per year in the United States to as high as 1400. Until a method for collecting such statistics is established, the true incidence will not be known. It is recognized, however, that it is the most common cause of mortality and accounts for the most long-term disability in infants and young children due to physical child abuse. The age of the victims range from the newborn period to 4 years of age. The vast majority of SBS/SIS occur before the infant's first birthday and the average age of the victim is between 3 and 8 months of age.
The usual trigger for shaking a baby is inconsolable crying in the infant. Frustrated by attempts to console the baby, the perpetrator loses control and grabs the infant, either by the chest, under the arms, or by the arms and violently shakes the baby. The time of shaking varies, usually ranging from around 5 seconds to 15 or 20 seconds. It has been estimated by video recordings of a person shaking a doll of approximate size and weight that the number of shakes ranges between 2 to 4 per second. During shaking, the head rotates wildly on the axis of the neck creating multiple forces within the head. The infant stops crying and stops breathing, causing decreased oxygen supply to the body, particularly to the brain. The infant brain, having a much higher water content that the adult brain, is much softer that an adult brain. The absence of myelination, the "insulation" of the nerve cells acquired during development of the nervous system, contributes to the relative softness. These factors make the brain more gelatinous and during shaking is more easily distorted and compressed within the skull. Shaking and the sudden deceleration of the head at the time of impact does several things:
  1. The veins that bridge from the brain to the dura, which is fixed to the inside of the skull, are stretched and, exceeding their elasticity, tear open and bleed, creating the subdural hematoma or subarachnoid hemorrhages or characteristics of the syndrome.
  2. The brain strikes the inner surfaces of the skull, causing direct trauma to the brain substance itself.
  3. The deeper structures of the brain, the axons, can be broken, shearing off during the commotion to the brain.
  4. The lack of oxygen during shaking causes further irreversible damage to the brain substance.
  5. Damaged nerve cells release chemicals which add both to oxygen deprivation to the brain and also cause direct further damage to the brain cells.

The combined effect is massive traumatic destruction of the brain tissue, leading to immediate brain swelling and causing enormous increases in the pressure within the skull. This swelling compounds the problem, since swelling causes compression of the blood vessels and decreases the oxygen supply to the brain.

It is these injuries to the brain, not the bleeding under the Dura or the Arachnoid Membranes that cause the signs, symptoms, and course of Shaken Baby/Shaken Impact Syndrome.

Concomitant with the destruction of the brain tissue are other injuries. The most significant of these are the retinal hemorrhages. There are a number of theories to explain retinal hemorrhages in SBS/SIS. One states that they are the result of transmitted pressure within the skull. The argument against this is that retinal hemorrhages occur with much less frequency in infants whose brain injuries are due to accidental causes with similar increased pressures within the skull, such as those resulting from motor vehicle accidents. Another theory is that retinal hemorrhages occur because shaking causes disruption of the layers of the retina. There are 10 layers on the retina, all richly supplied with blood vessels. Proponents of this theory state that when these layers are subjected to the lines of force associated with shaking, they slide across one another, stretching these vessels so that they also shear and bleed.

The retinal hemorrhages seen in SBS/SIS are variable ranging from a few scattered hemorrhages to extensive hemorrhages involving multiple layers of the retina. Retinal hemorrhages seen in other conditions are usually closer to the surface, so-called preretinal hemorrhages, and resolve quickly. Retinal hemorrhages are not seen as the result of cardiopulmonary resuscitation or accidental short falls.

A number of other lesions are variable findings in SBS/SIS. These include skull fractures resulting from the impact when the infant is thrown against a hard or soft surface; fractures of the posterior arcs of the ribs near the spine due to the levering of the fingers of the hands of the perpetrator while holding the baby during shaking; fractures of the clavicles (collarbone); and fractures of the long bones. Long bone fractures are attributed to the flailing of the arms and legs during shaking. Bruising of the skin of the head, face and body may also occur. It is uncommon to see injuries to the bones, interspinous ligaments and muscles of the neck, probably due to the underdevelopment of these structures in the infant. It is also uncommon to see injuries to the spinal cord in cases of SBS/SIS.

Symptoms and physical findings are variable, depending on the length and severity of the shaking and whether the infant was thrown onto a surface. The syndrome can be seen as a continuum from a short duration of shaking with little or no impact, to severe, prolonged shaking and major impact. The resulting signs and symptoms may run the gamut from decreased responsiveness, irritability, lethargy and limpness, - through convulsions, vomiting from increased pressure within the skull, increased breathing rate, low body temperature and low heart rate, - to coma with fixed and dilated pupils - to death. All of these symptoms are caused by generalized brain swelling secondary to trauma with these symptoms beginning immediately after the shaking and reaching their peak within 4-6 hours.

It is important to state that there is no evidence to support the concept that re-bleeding of an older subdural hematoma can result from trivial injury and cause an infant to suddenly collapse and die. The subdural bleeding is only significant in that it is a marker for the traumatic episode to the brain that produces all the clinical signs and symptoms. Even of such a re-bleeding should occur, it does not cause traumatic injury to the brain.

There is no evidence that the findings in SBS/SIS can result from accidental falls in the home, including falls down stairs, off beds or tables, or from caretaker's arms. SBS/SIS results from a violent inflicted injury producing immediate signs and symptoms.

Robert M. Reece, M.D.
Robert H. Kirschner, M.D.


    Materials are derived from the National Center on Shaken Baby Syndrome


 Costs Associated with SBS

Other Facts about SBS

The initial costs of hospitalization can easily be over $150,000. The Texas Brain Injury Association estimates that permanent brain injury costs could well reach $3 million dollars for a lifetime of care. The abusers rarely pay any of these costs. Victim families, taxpayers and insurance companies are responsible for these; rehabilitation, medical, special education and living expenses.

Children who continue receiving medical treatment and in-home nursing are typically at a cost of about $180,000 a year.

Some experts believe the costs could be as much as $15 million over a lifetime.


50% to 75% of adults and teenagers do not know that shaking a baby could be dangerous. The number of shaken baby survivors has not been documented. The Centers for Disease Control and Prevention estimate that abuse and neglect annually kill 5.4 out of every 100,000 children under age four. CDC also estimates that misclassification of childhood deaths probably means that this figure should be 11.6 out of every 100,000….more than the country's overall murder rate of 10 per 100,000. At least 2000 children die from abuse or neglect each year and another 18,000 are left permanently disabled. Most are under the age of four. Shaken baby syndrome accounts for an estimated 10-12% of all deaths due to abuse or neglect. Approximately ¼ of all children inflicted with SBS die and 41% of SBS victims are under the age of one. Experts say 1,000-1,500 cases of SBS occur each year in the United States, but the true number of cases is unknown because of misdiagnoses and underreporting. A baby can fall 3 stories and not get as seriously injured as a shaken baby. When a child is shaken in anger and frustration, the force is multiplied 5-10 times more than it would be if the child had simply tripped or fallen. If a baby has been shaken, it is important that it be taken to the hospital right away. Tell the doctor the baby was shaken so proper medical attention may be given.

Offenders and Vicitms of SBS


 Victim Profile

Offender Profile

Average age of victim 4-6 months 63% male 59% no previous record of abuse 30% die as a result of shaking 15% escape long term damage Toddlers as old as 4 years are at risk of serious injury Most survivors suffer long term disabilities


Average age of perpetrator 22 years 75% male 81% had no history of child abuse 75% had no history of substance abuse 50% were natural parents of the victims 37% biological father 21% boyfriends of the mother 17% female child care providers 12% mothers 13% other





The above statistics are from the

National Shaken Baby Coalition